[Compositional Variation of Spent Mushroom Substrate During Cyclic Utilization and Its Environmental Impact]

Area of Science:

• Agricultural Science
• Environmental Science
• Biotechnology

Background:

• Spent mushroom substrates (SMS) are byproducts of mushroom cultivation.
• Cyclic utilization and composting are potential disposal and valorization methods for SMS.
• Understanding nutrient dynamics and environmental risks is crucial for sustainable SMS management.

Purpose of the Study:

• To analyze nutrient composition changes in SMS during cyclic utilization and composting.
• To assess environmental risks associated with heavy metals and pollutant leaching.
• To evaluate the effectiveness of composting in organic matter degradation and nutrient stabilization.

Main Methods:

• Chemical analysis of protein, polysaccharide, lignin, cellulose, hemicellulose, C/N ratio, and humic acid content.
• Heavy metal concentration analysis (As, Hg, Pb, Cd, Cr).
• Column leaching tests to assess nutrient (N, P, organics) and pollutant (TN, COD) loss.

Main Results:

• Water consumption during reuse was 13.8%; protein and polysaccharide increased by 32.9% and 20.4% respectively.
• Composting reduced protein and polysaccharide by 50% and 79%, decreased C/N ratio, and increased humic acid by 18.6%.
• Heavy metal concentrations met NY525-2012 standards; leaching tests indicated potential N, P, and organic loss, but TN and COD accumulation decreased by 15.0% and 62.8% in compost leachate.

Conclusions:

• SMS retains significant nutrients during cyclic reuse.
• Composting effectively degrades organic matter in SMS and stabilizes nutrients.
• The composting process results in compost meeting heavy metal safety standards and reduces leachate pollution.